Bottom Chord Attic Not Connected

This anomaly did not make it into the 3rd printing of asce 7 10 in 2013 but did create a discrepancy in the 2012 2015 irc.

Bottom chord attic not connected.

Where ceiling joists are not parallel to rafters rafter ties shall be installed. D sketch the loading diagram and calculate the reactions. The design was 2 mono trusses sistered together at a ridge girder over the attic space. The remaining portions of the bottom chords shall be designed for a uniformly distributed concurrent live load of not less than 10 lb ft2 0 48 kn m2.

Where ceiling joists are not connected to the rafters at the top wall plate joists connected higher in the attic shall be installed as rafter ties or a continuous tie should be provided. Lay a 2 by 4 across the truss with its bottom end on the top edge of the lower cord and centered on the mark you made between the end of the truss and its center. See table r301 5 for the above and then this note below the table. Attics without storage are those where the maximum clear height between joist and rafter is less than 42 inches or where there are not two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high by.

A triangle is the simplest form of a truss and the bottom chord is the base piece. The bottom chord therefore carries combined stress of both tension and bending of the truss. The attic space is considered uninhabitable but will be used for storage. About the bottom chord.

Recently a project came across our desk that was an unusual attic design. Plating o do not reduce minimum plating defaults. The horizontal beam of the triangle of a bottom chord is used in this simple triangle truss construction. The architect had drawn in an attic condition that stepped up and over the floor joists at one end of the building.

O no top chord splices in haunch of attic room as shown below. Attic with storage is 20 psf versus 10 psf for attic with no storage. Several common wood truss splice joint configurations were tested at varying levels of. A rafter tie forms the bottom chord of a simple triangular roof truss.

O no bottom chord splice directly over a bearing within a room. It s okay to do this. Center the 2 by 4 on the mark on the upper cord as well so that it extends from the lower cord at a 90 degree angle. A the top and bottom chord dead load.

Toenail a truss into the top of the wall plate by nailing through the sides of the bottom chord at a 30 degree angle. Metal plate connected mpc splice joints were tested in combined tension and bending to generate data that were used in the development of a design procedure for determining the steel net section strength of bottom chord splice joints of mpc wood trusses. B the top chord live include snow load as a live load and bottom chord live load. C determine the total load and proper load duration.